Chain saw lubricating system



Nov. 28, 1961 L. M. STRUNK 3,010,538

CHAIN SAW LUBRICATING SYSTEM Filed Jan. 6, 1958 2. Sheets-Sheet lINVENTOR. LEON HRD M. STRUNK.

F7 TTORNEV United States Patent 3,010,538 CHAIN SAW LUBRICATING SYSTEMLeonard lVI. Strunk, R.D. 4, Coatesville, Pa. Filed Jan. 6, 1958, Ser.No. 707,321 1 Claim. (Cl. 184-15) This invention relates generally topower-driven handsupported chain saws used primarily for felling andbucking trees, and more particularly to certainimprovements in that typeof chain saw which is the subject of United States Letters Patent No.2,748,810, issued to Leonard M. Strunk on June 5, 1956.

A principal object of the present invention is to provide for a chainsaw of the type aforesaid improved means for delivering a lubricant tothe saw bar.

Another object of the present invention is to provide for a chain saw ofthe type aforesaid a lubricating system including a pump operable forclearing the channel through which the lubricant is delivered to the sawbar should the same become clogged with saw dust or dirt.

Other objects and advantages of the present invention will appear morefully hereinafter, it being understood that the present inventionconsists substantially in the combination, construction, location andrelative arrangement of parts, all as described in detail in thefollowing specification, as shown in the drawings and as finally pointedout in the appended claim.

In the accompanying drawings:

FIGURE 1 is a side elevation of a chain saw constructed in accordancewith and embodying the principles of the present invention.

FIGURE 2 is an enlarged view of the saw chain side of the saw, the sawbar and the saw chain being omitted.

FIGURE 3 is a front elevation of the saw with part in section, showingdetails of the arrangement for lubricating the chain.

FIGURE 4 is a side elevation of the fuel and oil tank.

FIGURE 5 is a fragmentary plan view as indicated by line 5-5 of FIGURE4.

FIGURE 6 is a rear elevation of the fuel and oil tank.

FIGURE 7 is an enlarged section on line 7-7 of FIGURE 4.

FIGURES 8 and 9 are similar to FIGURE 7 but respectively show thecondition of parts when there is a normal flow of oil and when the pumpis being used to restore a normal flow of oil.

FIGURE 10 is a section on line 10-10 of FIGURE 7, showing the meteringvalve closed. 7

FIGURE 11 is an exploded view of the pump plunger and its head.

Referring to the drawings, the exemplary chain saw constructed inaccordance with and embodying the principlm of the present inventioncomprises an internal combustion engine 10, a conventional carburator 11positioned to the rear of and connected to the engine, a topmountedcompartmented fuel and oil tank 12, a conventional magneto and enginestarter within an air shroud 13 at one side of the engine, a side framecasting 14 at the opposite side of. the engine, a power shaft 15extending through the side frame casting, a sprocket 16 and a clutch 17mounted upon the power shaft, a forwardly projecting saw bar 18supported by the side frame casting, a saw chain 19 trained over thesprocket and the saw bar, an encircling handle 20, and a rear supportingleg 21 disposed beneath the carburator.

The power shaft 15, which preferably is an extension of the enginecrankshaft, projects through a centrally apertured well 22 formed on theinner or engine side of the side frame casting 14. The saw bar 18 issecured in flatwise assembly relation with the side frame casting 14 bya retainer plate 23 and a pair of studs 2424.

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The saw bar 18 is provided along its upper and lower longitudinallyextending edges and along its rounded front edge with a continuouslyextending chain guiding channel, groove or slot 25, which slot is ofadepth sufficient to accommodate therein the chain guide wingsconventionally provided on the inner edges of the chain links and whichguide wings, designated 26, are adapted for engagement with the teeth ofthe sprocket 16 for driving of the saw chain 19 about the saw bar 18. Itwill be appreciated that efficient operation of the saw requires thatadequate provision be made for abundantly supplying the saw chain 19 andthe guiding groove 25, in which the saw chain runs, with a suitablelubricant. The present invention meets this requirement in the mannernow to be described.

The compartmented fuel and oil tank 12 includes, in addition to an oilreservoir, designated 27, for supplying lubricating oil to thechain-traversed saw bar 18, a compartment 27a in which is stored fuelfor the engine 10. This tank is mounted so that the oil compartment 27is elevated above the upper run of the saw chain during all normalpositions of use of the saw. To this end, the tank 12 is provided alongits bottom with a longitudinally extending supporting rib 28 which isembraced by a pair of angle members 29-29 suitably secured together bybolts 30. The oppositely extending base flanges of the angle members29-29 are respectively secured, as by bolts 31 to a flat plate 32, whichin turn is suitably secured to the engine body also by the bolts 31, theplate 32 being supported in suitably spaced relation to the engine bodyby spacers designated 33, embracing the shanks of the bolts 31 below theplate 32. Preferably, the tank mounting is such that the tank 12 isspaced fromand generally parallels the top side of the engine 10.

A fitting .34 is threaded into the front of the crankcase body,designated 35, of the engine, and a pressure, line 36 extends from thefitting 34 rearwardly under and then upwardly around the back of thecrankcase body 35, within the air shroud 13. Then the line 36 extendsthrough the air shroud 13, makes a loop 37 and connects to a check valve38, which latter is threaded into the roof of the oil reservoir 27, nearthe partition which sepa-' rates the oil and fuel compartments. The line36 serves to place the interior of the engine casing in communicationwith the oil reservoir 27. Since, in the normal operation of the engine10, the interior of the engine casing is under pressure, in the order of5 p.s.i., the oil reservoir 27 is likewise under pressure, inconsequence of which oil is discharged from the oil reservoir 27 underpressure through an oil line section 39 connected into one side oftheoil reservoir 27 and extending to the rear of the tank 12 for connectionto unitary means, generally designated 40, adapted for controlling theflow of oil.

Extending from the unitary control means 40 forwardly between the tank12 and the engine 10, then transversely over the engine 10 and finallyforwardly to a fitting 41 is a second oil line section 42. The fitting41 is threaded into the inner end of a passage 43, which passage ex:tends through the casting 14 and communicates with the chain guidegroove 25, as by suitable passages 44 formed in the saw bar 18. g

The unitary control means 40 comprises a main body 45 fitted to the rearof the tank 12 and secured thereto by a screw 45a and having formedtherein an upstream oil passage 46, a downstream oil passage 47 axiallyaligned with the passage 46, a bore 48 normal to and extending laterallyfrom between the passages aforesaid, and an oil passage 49 normal to andextending laterally from the downstream oil passage 47 in parallelspaced relation to the bore 48. The upstream and downstream oil passages46 and 47 communicate with the inner end of the bore 48 respectivelythrough constricted passage por- 'ing off the supply of oil.

3 tions 50 and 51, and the downstream oil passage 47 communicates withthe inner end of the oil passage 49 through a constricted passageportion 52.

Threaded into the outer end of the upstream oil passage 46 is a fitting53, to which fitting the oil line sec-- tion 39 isconnected. Within thispassage is a valve 54, which valve is seated over the outlet end of thefitting 53,, being yieldably secured in position by a compression coilspring 55. Threaded into the outer end of the downstream oil passage 47is a plug 56,and within the oil passage 47 is a valve 57, which valve isseated over the constriction 51, being yieldably secured in position bya coil spring 58.

Threaded into the outer end of the bore 48 is a sleeve 59, through whichsleeve slidably projects a plunger 60 that is provided with a head 61slidably fitted in the bore 48. The sleeve 59 is provided with a bonnet62 that overlies a suitable packing 63. Under the head 61 is acompression coil spring 64 that acts to bias the plunger 60 outwardly.

Threaded into the outer end of the oil passage 49 is an adapter 65, andthreaded into the latter is a needle valve 66, which needle valveincludes a main body 67, a stem 68, a bonnet 69, and an operating knob70. The outlet end of the valve 66 is connected with the oil linesection 42 through the medium of a fitting 71.

In the operation of the chain saw, the oil reservoir 27 is pressurizedin the manner already described, in consequence of which oil flows fromthe oil reservoirand courses successively through oil line section 39,unitary control means 40, the second oil line section 42, the oilpassage 43, and the oil passage 44 to the chain guide groove 25 of thesaw bar 18. .It will be noted, of course, that the oil delivered to thechain guide groove 25 is not returned to the reservoir 27, and hence thelubricating system is of the open-loop or non-return type. The flow ofoil may be regulated by manipulating the needle valve 66. a

, Normally, the pressure exerted by the oil upon the valves 54 and 57 issuflicient for unseating the same against the influence of the coilsprings 55 and 58, in consequence of which oil courses freely from thetank 12 to the saw bar 18 in the manner aforesaid. However, itfrequently happens that the oil passage upon the downstream side of theunitary control means 40 becomes clogged with dirt, saw dust or otherforeign matter, chok- In this event, the plunger 60 is depressed tothereby clear the oil line of the obstruction.

Initial movement of the plunger 60 removes the pressure from the valve54, which latter then closes under the influence of the spring 55.Continued movement of the plunger 60 then forces the column of oil underthe head 61 of the plunger downstream'past the valve 57, in consequenceof which the obstruction is dislodged and ejected from the oil channel.

When the plunger 60 is released, it is moved outwardly under theinfluence of the coil spring 64. Initial movement of the plunger 60causes a suction that tends to draw oil back through the valve 57, whichis precluded oil line. In order to provide the necessary freedom ofmovement for the plunger 60, a bleeder opening 72 for ceptible ofvarious changes and modifications which may be made from time to timewithout departing from the real spirit or general'principles of theinvention. For example, while preferablythe oil supply is pressurized,oil could be delivered from the oil reservoir to the saw bar simply bygravity flow. In addition, hinged type check valves could be utilizedinstead of the ball and coil spring ty-pe check valves shown anddescribed. Furthermore, the metering valve 66 and the check valve 57,while desirable, are not essential. Still further both check valves 54and 57 could be eliminated and an ordinary manually operated valvesubstituted for the check valve 54. Accordingly, it is intended to claimthe same broad- 1y as well as specifically as indicated by the appendedclaim. 7

What is claimed as new and useful is:

In a portable chain saw of the type powered by an internal combustionengine having a laterally projecting power take-oil shaft adapted fordriving-an endless saw chain trained about a drive sprocket and a sawbar extending freely beyond the front end of said engine, an open-looplubricating system for lubricating the saw chain and saw bar comprising,an oil reservoir, a pressurizing line communicating between saidreservoir above the oil level and the interior of the engine housing toplace the oil in the reservoir under greater than atmospheric pressurewhen the engine is operating, an oil line operatively connecting saidreservoir with said saw bar for delivery of oil to the latter, a pair ofspring biased check valves series connected in said oil line to permitoil flow therethrough in the same direction, said valves automaticallyclosing under spring bias to prevent delivery of oil from said reservoirto the saw bar when the engine is not operating and opening to permitoil flow therethrough responsive to the increased oil pressure when theengine is operating, and a single action plunger reciprocable within acylinder connected in said oil line between said unidirectional valves,said plunger being operative upon each. working stroke to close theupstream valve against the valve-opening force of the pressurized oiland simultaneously to force oil through the downstream valve and theportion of said oil line upon the downstream side of the latter tothereby clear the same of any obstruction that may be impeding the freeflow of oil, and being operative upon each return stroke to close thedownstream valve against thevalveopening force of the pressurized oil tothereby avoid drawing oil back into the cylinder and simultaneously toopen the upstream valve to thereby draw a fresh supply of oil into thecylinder.

References Cited in the file of this patent UNITED STATES PATENTS1,878,167 Muller Sept. 20, 1932 2,605,787 Kiekhaefer Aug. 5, 19522,748,810 Strunk June 5, 1956 2,840,035 La Porte June 24, 1958 2,944,538Conway et a1. July 12, 1960 FOREIGN PATENTS 7 295,454 Switzerland May 1,1954

